1) すると →Then 2) こゆびくらいの →about the size of a little finger 3) おとこのこが → A boy 4) つちも(?) → I think that it's maybe written in other Hiragana, so I can't explain it. すると、こゆびくらいのおとこのこがあらわれた (Then, A boy about the size of a little finger appeared.)